Kaivalya Upanishad Mantra
Turn your attention to the steady, pure, clear, and pleasant lotus-like heart and meditate there on unborn all-pervading Existence shining as formless blissful Consciousness, the source of everything, incomprehensible, unmanifest, auspicious, wonderful, tranquil, immortal, without beginning, middle or end.
During the waking state, the mind pervades all over the body because it is interacting with the external world. The śāstras say that the mind resolves into the heart when not it is not functioning, as it does in deep sleep state. Heart is the location of the mind. Even though Bhagavan is all pervading, at the time of meditation, heart is the location of Īśvara. Thus, the Lord is invoked only in the mind because Bhagavan is in the mind as the sākṣi caitanyam; the witness of the presence and absence of thoughts. The whole body is a temple, the kośas are like the various levels leading up to the Heart, where the lord is installed as one non-dual deity.
